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A small chimerically bifunctional monomeric protein: Tapes japonica lysozyme
K Takeshita1, Y Hashimoto, T Ueda
1Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
Cellular and Molecular Life Sciences : CMLS
|October 3, 2003
Summary
Marine clam lysozyme exhibits novel isopeptidase and chitinase activities. These distinct enzymatic functions, found in Tapes japonica lysozyme, operate at different pH levels and active sites.
Area of Science:
- Biochemistry
- Marine Biology
- Enzymology
Background:
- Lysozymes are enzymes known for their antimicrobial properties.
- The lysozyme from the marine bivalve Tapes japonica is a novel protein.
- This lysozyme shares homology with destabilase from medicinal leech, suggesting potential unique activities.
Purpose of the Study:
- To investigate the enzymatic activities of Tapes japonica lysozyme.
- To characterize the chitinase and isopeptidase activities of this novel protein.
- To determine if these activities occur at distinct active sites.
Main Methods:
- Hydrolysis assays using specific substrates (L-gamma-Glu-pNA, D-gamma-Glu-pNA, epsilon-(gamma-Glu)-L-Lys).
- Determination of optimal pH for chitinase and isopeptidase activity.
- Inhibition studies using a serine protease inhibitor.
- Assessment of activity changes after lyophilization.
Main Results:
- T. japonica lysozyme demonstrated hydrolysis activity against the tested substrates.
- Optimal pH for chitinase activity was 5.0, and for isopeptidase activity was 7.0.
- Isopeptidase activity was inhibited by a serine protease inhibitor and reduced by lyophilization, unlike chitinase and lytic activities.
Conclusions:
- T. japonica lysozyme possesses both chitinase and isopeptidase activities.
- These distinct enzymatic activities are likely located at different active sites within the protein.
- The differential sensitivity to inhibitors and lyophilization supports the conclusion of separate active sites.